Prospective study of serum and ionized magnesium pharmacokinetics in the treatment of children with severe acute asthma.

PURPOSE: Intravenous (IV) magnesium sulfate (MgSO4) is clinically useful as adjunct therapy in treating acute asthma exacerbations. Despite its clinical utility, the disposition of magnesium in children is poorly described. The purpose of this study is to describe the pharmacokinetics (PK) of ionized and total serum magnesium following IV MgSO4 administration in children with severe acute asthma. METHODS: Thirty-two children receiving 50 mg/kg IV MgSO4 for acute asthma exacerbations at Primary Children's Hospital in Salt Lake City, UT, were prospectively enrolled in the study. Blood samples were collected before, as well as 30 min and 2 h after each child's IV MgSO4 dose, and used to determine total serum and ionized magnesium concentrations. The collected data were analyzed using population PK techniques using NONMEM® software. RESULTS: Total serum magnesium concentrations were used to externally validate our previously published model constructed with retrospective data (median prediction error 10.3%, median absolute prediction error 18.1%). The mean (%CV) observed endogenous ionized magnesium concentration was calculated to be 6.0 mg/L (12%), approximately one third of the same value for endogenous total serum magnesium (17.6 mg/L (22%)) in this dataset. Weight was a significant predictor of both clearance and volume in a population PK model describing ionized magnesium concentrations. No adverse events were observed in this pediatric cohort. CONCLUSIONS: This prospective study supports and extends our previous PK analysis of total serum magnesium concentrations. Ionized and total serum magnesium followed similar PK profiles following IV MgSO4 administration in children. A single bolus infusion of IV MgSO4 was safe in this small sample of children receiving it for acute asthma.

Antibiotic Treatment of Suspected and Confirmed Neonatal Sepsis Within 28 Days of Birth: A Retrospective Analysis.

Neonatal sepsis causes significant mortality and morbidity worldwide. Diagnosis is usually confirmed via blood culture results. Blood culture sepsis confirmation can take days and suffer from contamination and false negatives. Empiric therapy with antibiotics is common. This study aims to retrospectively describe and compare treatments of blood culture-confirmed and unconfirmed, but suspected, sepsis within the University of Utah Hospital system. Electronic health records were obtained from 1,248 neonates from January 1, 2006, to December 31, 2017. Sepsis was categorized into early-onset (≤3 days of birth, EOS) and late-onset (>3 and ≤28 days of birth, LOS) and categorized as culture-confirmed sepsis if a pathogen was cultured from the blood and unconfirmed if all blood cultures were negative with no potentially contaminated blood cultures. Of 1,010 neonates in the EOS cohort, 23 (2.3%) were culture-confirmed, most with Escherichia coli (42%). Treatment for unconfirmed EOS lasted an average of 6.1 days with primarily gentamicin and ampicillin while confirmed patients were treated for an average of 12.3 days with increased administration of cefotaxime. Of 311 neonates in the LOS cohort, 62 (20%) were culture-confirmed, most culturing coagulase negative staphylococci (46%). Treatment courses for unconfirmed LOS lasted an average of 7.8 days while confirmed patients were treated for an average of 11.4 days, these patients were primarily treated with vancomycin and gentamicin. The use of cefotaxime for unconfirmed EOS and LOS increased throughout the study period. Cefotaxime administration was associated with an increase in neonatal mortality, even when potential confounding factors were added to the logistic regression model (adjusted odds ratio 2.8, 95%CI [1.21, 6.88], p = 0.02). These results may not be generalized to all hospitals and the use of cefotaxime may be a surrogate for other factors. Given the low rate of blood culture positive diagnosis and the high exposure rate of empiric antibiotics, this patient population might benefit from improved diagnostics with reevaluation of antibiotic use guidelines.